Cosmetic sticks are well known for use in delivering a number of different agents to the skin. Such sticks are often constructed of wax-type materials or gelling agents such as soaps. The desire to get the best of both types of products has led to a variety of product executions.
Among the product executions which have been developed are deodorant and antiperspirant sticks. Included are deodorant and antiperspirant sticks which deliver active ingredients to the skin via a vehicle which glides easily over the skin surface and which imparts a cooling sensation to the skin both during and after application. Soap/alcohol gels can provide such cosmetic benefits. However, incorporation of conventional astringent antiperspirant salts into such gels tends to interfere with the gel structure and render it less cosmetically desirable. To solve such compatibility problems, soap/alcohol gel sticks have been formulated using special additives such as lactate salts. (See, for example, Teller; U.S. Pat. No. 2,732,327, issued Jan. 24, 1956 and Slater; U.S. Pat. No. 2,900,306, issued Aug. 18, 1959). Some soap/alcohol gel antiperspirant sticks have also been formulated in two phases with an inner core containing gel-compatible antiperspirant salts and an outer shell containing deodorant materials (See Bell, U.S. Pat. No. 2,970,083, issued Jan. 31, 1961).
Combination of a conventional waxy antiperspirant composition with a soap/alcohol gel to form a two-phase stick composition could enhance composition efficacy and improve composition cosmetic benefits. Such combination is, however, not made without certain difficulties. While each phase alone of such a stick composition is stable, contact between the two phases can cause destructive interaction between the two phases. The alcohol/gel phase experiences syneresis which is a bleeding or leading of the gelled alcohol from the gel structure or matrix. Such leaked alcohol can interact with components of the waxy phase and can thus consume or physically separate the phases, thereby resulting in an unacceptable consumer product.
These problems led to the development described in U.S. Pat. No. 4,202,879, May 13, 1980 to Shelton. Shelton's invention relates to the use of a thin waxy barrier between the phases. The method of applying the barrier, which is described at lines 35-50 of Column 15 in the patent, involves dipping the solidified inner phase of the stick into a bath containing the molten barrier mixture, removing the coated inner phase from the bath, letting the barrier solidify, placing the solidified barrier coated inner phase into a mold and adding the molten outer phase into the space between the coated inner phase and the wall of the mold. This approach, while providing a barrier phase, has been found to be not entirely satisfactory. Difficulties were encountered in handling the coated inner phase and in making the total product quickly.
In view of the aforementioned problems, there is the need for improved processes for placing a barrier between two incompatible phases. It is, therefore, an object of the present invention to provide an improved process for providing such barriers.
It is a further object of the present invention to provide a process for providing multi-phase antiperspirant sticks.
It is a further object of the present invention to provide such antiperspirant sticks in a fast and economical manner.
It has been surprisingly discovered that these objectives, which will become apparent from the following detailed disclosure, can be realized by coating a pin and then releasing the coating to the outer phase.
All percentages herein are by weight unless otherwise specified.